In the packaging of many liquid household products, e.g., window cleaners, insect poisons, cleaning fluids, etc., it has been found market-attracrive to include, as part of the package, a finger actuated dispensing pump. These pumps are generally fitted with nozzles which are capable of product delivery in a spray mode and/or a stream mode. Most nozzles produce the spray mode by causing the liquid product to be broken up into small particles as it is dispensed in a vortical state from the nozzle. The desired vortex is generally formed by forcing the liquid to traverse a swirling path as the liquid exits the nozzle outlet orifice. The swirling path can be accomplished by the use of any of the well known "swirl chamber" devices which are associated with the nozzle. See for example the devices of U.S. Pat. No. 4,358,057; U.S. Pat. No. 4,257,751; and U.S. Pat. No. 4,161,288.
The spray mode of delivery is preferred over the stream mode in those applications where the product is to be applied evenly over a relatively large area. However, due to the break-up of the liquid, some of the product will be delivered as a fine mist. Also a fine mist can be formed when the product impacts the surface on which it is sprayed. When the product is applied in an enclosed area, e.g., a shower stall, there is the possibility that the user will inhale some of the mist. Even in open areas, the mist is apt to settle where not desired, e.g., the user's wearing apparel. When the product is toxic or corrosive, this inhalation and settling is undesirable if not blatantly dangerous.
To overcome the problems created by the fine mist, the pump industry has tried aeration of the small liquid particles subsequent to their exiting the swirl chamber. Such aeration gives at least a portion of the dispensed liquid a foam characteristic which does not yield the unwanted fine mist--indeed the foamed liquid is further beneficient in that it entraps any fine mist which comes into contact with it. Aeration of the small liquid particles is conventionally achieved by providing an open ended chamber which surrounds and extends outwardly of the nozzle outlet orifice and which has air aspirating ports generally located between the nozzle outlet orifice and the open end of the chamber. The thus aspirated air is then entrained in the dispensed liquid to achieve the aeration. Generally, these aspiration ports are located between the nozzle outlet orifice and the back-side of the vortex formed by the swirl chamber.
A different approach is provided by the nozzle disclosed in my co-pending application, Ser. No. 659,684, filed Oct. 11, 1984 now U.S. Pat. No. 4,669,665 granted June 2, 1987. The nozzle disclosed therein achieves foam formation principally by aeration of a turbulent film of the product to be dispensed. To produce the turbulent film, the nozzle first causes the formation of a vortex of the product and then causes the vortex to impinge, at its base end, on a wall of a nozzle furnished chamber. The chamber surrounds and extends outwardly from the nozzle outlet orifice and is closed off to aspirated incoming air flow except from its discharge end. The aspirated incoming air encounters the turbulent film in a principally counter-current manner.
It is an object of this invention to provide an improved foam-dispensing nozzle, which nozzle provides for high aeration of the dispensed product.